A creep model for soil-rock mixture considering the effect of rock contents and freeze-thaw cycles

The complicated heterogeneity and discontinuity of soil-rock mixture (SRM) usually cause high variability in SRM's creep characteristics, which can easily cause geological disasters (e.g., landslides) under harsh environment such as freeze-thaw (F-T) cycles. However, the nonlinear creep behaviors of SRM material, under varying internal structures induced by F-T cycles, skeleton changes and stress states, have not been reported and it is still challenging to describe these complicated creep behaviors using current existing creep models. Therefore, direct shear creep tests were carried out to study the creep evolutions of SRM under various F-T cycles (0 to 15 cycles) and rock contents (15% to 55%). A new element combination creep model was then proposed to describe SRM's nonlinear creep behaviors involving the instantaneous elastoplastic and viscoelastic-plastic deformations. Results showed that the creep deformation tended to decrease as the rock content increased. The initial 3 to 5 F-T cycles significantly affected the creep behaviour of SRM. The proposed new creep model could well describe the nonlinear creep behaviors of SRM material under different stress states.